Restudy of acid-extractable hydrocarbon data from surface geochemical survey in the Yimeng Uplift of the Ordos Basin, China: Improvement of geochemical prospecting for hydrocarbons
- 作者：Liuping Zhang ; Guoping Bai ; Kebin Zhao and Changqing Sun
- 关键词：Hydrocarbons ; Geochemical exploration ; Interference ; Anomalies ; Data processing
- 刊名：Marine and Petroleum Geology
- 出版年：2006
- 期刊代码：37_02648172
- 类别：pw
- 出版时间：June 2006
- 卷：23
- 期：5
- 页码：529-542
- 文件大小：1446 K
摘要
Two geochemical surveys were conducted in 1992 and 2000 respectively in the Yimeng Uplift of the Ordos Basin, China. The earlier survey grid had 1×5 km spacing and the later survey grid had 0.5×0.5 km spacing. The acid-extractable hydrocarbons of both surveys show similar geochemical trends. However, the anomalies obtained with traditional statistical methods do not correlate with existing oil/gas fields. This study reveals two problems in the data and their processing. The first one is interference caused by the variation of soil composition. We applied a wavelet-analysis-based method to eliminate this interference in the data of the later survey. The second is that micro-seepage anomalies did not identify existing oil/gas fields and seepage anomalies related with faults had not been previously recognized. We modified the logic multiplication cluster analysis and applied a multi-fractal model and a back propagation artificial neural network to recognize these two types of anomalies that cannot be recognized with typical statistics in the study area. The recognized seepage anomalies display a string-bead-shaped pattern and some are distributed along a large fault in this area. The fault is the main pathway for hydrocarbon migration. The micro-seepage anomalies are ring-shaped and are mostly distributed close to the fault. They coincide with oil/gas field and structure traps. Therefore, reprocessing of existing geochemical data using these new methods can greatly improve their usefulness in hydrocarbon exploration.